Preparation and Properties of Poly(lactic Acid)/Thermoplastic Starch/Reduced Graphene Oxide Composites

Abstract

Glucose‐reduced graphene oxide (rGO‐g) is incorporated in thermoplastic starch (TPS)/polylactic acid (PLA) 1:1 immiscible blend by one‐step extrusion. X‐ray diffraction shows increased crystallinity for TPS/PLA/rGO‐g composites and intercalation of rGO‐g lamellae. Differential scanning calorimetry indicated that the rGO‐g filler induced crystal nucleation in the composites. Scanning electron microscopy images obtained for the composites presented improved adhesion between the phases. Thermogravimetric analysis results showed improvement in the maximum degradation rate (Tmax) for TPS and for PLA phases in the composites. Tensile tests revealed increase of rigidity of the composites in relation to the neat blend, reaching 10‐fold increase of the Young's modulus for the composition with rGO‐g incorporated at 5.0% mass content. The presence of rGO‐g intercalated lamellae resulted in a small volume of conductive pathways, which led to conductivity values around σ = 10−8 and 10−7 S cm−1 for the composition with rGO‐g incorporated at 3.0 and 5.0% mass content, respectively.

Surfactant-Free Stabilization of Aqueous Graphene Dispersions Using Starch as a Dispersing Agent

“… 23 , 24 In general, the interfacial interaction between GO/RGO and starch is commonly attributed to hydrogen bonding via their oxygen groups, respectively. 25 − 27 While these oxygen-rich GO/RGOs resemble the geometric dimension of pristine graphene, their surface properties and functions are substantially different compared to the pristine graphene. Therefore, the same stabilization mechanism is not expected in the dispersion of graphene.…”

“…However, impurities on the surface substantially limit the properties of graphene. To restore these properties, starch was also explored as a reducing agent to remove these oxygen groups and functionalize the resulting reduced GO (RGO). , In general, the interfacial interaction between GO/RGO and starch is commonly attributed to hydrogen bonding via their oxygen groups, respectively. − While these oxygen-rich GO/RGOs resemble the geometric dimension of pristine graphene, their surface properties and functions are substantially different compared to the pristine graphene. Therefore, the same stabilization mechanism is not expected in the dispersion of graphene.…”